The research proposed applies the most recent techniques for high resolution thermal denaturation of DNA to the physical characterization of simple genomes. In addition, the experiments should test the validity of the hypothesis that thermal subtransitions in DNA are related to individual genes and investigate the possibility that unique physical structures at local sites in DNA may determine the ends of a cooperatively interacting sequence of bases. This investigation has been proposed because recent advances in methods for recording and analyzing thermal transitions of pure DNA provide denaturation profiles that contain vastly more information than previously was found in traditional melting curves.